There are erosion control fabrics which look like nets. Most are only available through landscape contractors or supply houses, though. Or, if you plant on planting the hillside or putting bark or some other decorative material, you can cover the slope with weed barrier landscape fabric. It has tiny holes which allow some moisture to penetrate, but it will shed most of the rainwater which will slow erosion. Once you plant something with fibrous roots, the bank or slope will be more stable. Best wishes with your landscape.